If you are new to canning at home or safe food preservation, there are undoubtedly many questions. How can you be certain home canned foods are safe to eat? What is the processing time required for different foods? What’s the minimum temperature needed to make canned foods safe? Which equipment is best for home canning? How can I be sure home canned food is microorganisms free?
Thankfully there have been major improvements in published information, techniques, equipment and guidelines during the last 30 years. Today, many government and commercial websites, which are easy to access, offer information on how to preserve foods safely.
Visit sites like The National Center for Home Food Preservation for extensive articles on how to can, freeze, dry, cure & smoke, ferment or pickle foods. Ball Corporation, makers of canning jars, lids and supplies, offers recipes, canning techniques and products. Both websites offer easy to follow instructions for food preservation that are backed by years of research and extensive testing.
1. Understanding the canning process
Canning is simply one step beyond cooking. Canning applies heat to food in a closed canning jar to stop the natural spoilage that would otherwise take place. The process removes air from the jar to create an airtight seal.
2. There are two basic home canning methods: water bath canning and pressure canning
Water Bath Canning
This is the most common technique used for high-acid foods. It is ideal for canning fruits, fruit juices, jams and jellies, salsas, tomatoes with added acid, pickles, relishes, chutneys, sauces, vinegars and condiments.
Water bath canners will include a pot with a fitted lid and usually a wire rack to keep the glass jars off the bottom of the pot.
To preserve low acid fruits and vegetables, meats, poultry and seafood, Pressure canning is mandatory for safety. Pressure canning heats the contents to 240º F, and therefore eliminates the risk of foodborne bacteria. If you’re mixing high acid foods with low-acid foods you must use the pressure canning method.
Modern pressure canners, those manufactured after the 1970s will have an automatic vent/cover lock, a steam vent and a safety fuse. I prefer the made in the US models with a weighted gauge instead of the dial gauge, which needs to be calibrated periodically. Choose one that is Underwriter’s Laboratory (UL) approval to ensure safety. The USDA recommends that a canner be large enough to hold at least 4 quart jars to be considered a pressure canner for the USDA published processes.
3. Keep it clean
The purpose of canning is to heat the food to a high enough temperature to arrest enzymatic activity and kill yeasts, molds and bacteria. To help avoid foodborne illness clean all the equipment and supplies at the beginning of the canning process in boiling water. Canning equipment and recipes will provide detailed instructions on the correct procedure for this.
4. Allow the proper processing time for each different food
It is important to closely follow guidelines for each recipe. Process times will vary by food and by altitude. Processing times will be included in any legitimate recipe source. Instructions on how to adjust for altitude will come with your canner or can be found at the websites listed above.
The Ball Corporation publishes the Ball Blue Book Guide to Preserving. Now in its 37 edition, has 128 pages of canning information, recipes and instructions ISBN-10: 0972753702 under $10.00. Available on Amazon and other retailers.
The Complete Guide to Home Canning and Preserving by the US Department of Agriculture, 192 pages of canning and preserving information ISBN-10: 0486409317 under $10.00. Available on Amazon in paperback and Kindle editions and from other retailers.